arXiv AI By Pranjal Garg

How High Is 0.6? Floors, Ceilings, and Headroom in Interpretability Probing

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The paper argues that probe scores lack intrinsic meaning and should be interpreted relative to two reference points: a floor (what simple inputs predict) and a ceiling (what the full input predicts). The difference, called headroom, indicates the range where a probe can reveal that a model computes beyond what the input already provides. Experiments on transformers and real models show that headroom can vanish when the target no longer depends on hidden variables or when the input no longer reveals them, and that some previously claimed representations are largely explained by the input text alone.

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